Evaluation for Machinery

We propose a simplified algorithm (inspired by the GCS and multiple personal driving experiences, as well as assessment of thousands of patients) for such evaluation with the stipulation that it should be viewed as a suggestion rather than a prescription (Table 17.2).

Table 17.2. Proposed driving or machinery operating disability scoring matrix.

Task or manifestation

Normal or better

Somewhat impaired ("leaning positive")

Definitely impaired ("leaning negative")

Incompatible with safe driving/ operating of machinery

Visual field and acuity Impulsivity and risk-taking Speed of response Motor function Seizure or pseudoseizure disorder diagnosis Seizure-free for more than

18 months Pseudoseizures presenting with abrupt loss of control Sleep disorder suspected Sleep apnea or other drowsiness-inducing diagnosis Present alcohol or recreational abuse Dementia present (based on MMSE scores or similar assessment)

MMSE, Mini-Mental Status Examination.

The physician should assess the patient and decide on the impressions: is the patient unimpaired (column A); is the patient impaired but seeming to compensate effectively (column B); are the patient's attempts to compensate inadequate (column C); or is the patient's presentation that of decompensation (column D)? Summation of the corresponding number scores produces the disability index (ideally, in a healthy patient this index is 0, while a severely impaired patient may present with the maximum score of 51). The severity indices (number in the table's cells) are based on published studies, for example, Teran-Santos et al. (31), who reported that patients with an apnea-hypopnea index of 10 or higher had an odds ratio of 6.3 (95% confidence interval [CI] = 2.4 -16.2) of having a traffic accident within a year (32).

A similar approach led to the assignment of indices for seizure disorders. Ever since Waller's research, epilepsy patients with poor compliance in taking their anticonvulsant medication, and patients who are young and abuse alcohol are justifiably believed to pose the highest risk of driving or machinery accidents. At the same time, the literature suggests that patients with seizures without loss of consciousness pose no increased risk, while those with an established pattern of exclusively nocturnal events, as well as those with consistent and prolonged auras, have much less risk than the Waller's "deviant" group. It is worth noting that the consensus statement approved in

1994 by the American Epilepsy Society and the American Academy of Neurology recommended a minimum seizure-free interval of only 3 months, although legal requirements vary widely among states (33).

In Parkinson's disease even moderate severity is often severely disabling due to the inability to initiate and stop motion, an absolute necessity in operation of all machinery. Distance judgment may also be impaired early in the disease and should be assessed separately. Patients with stroke, multiple sclerosis, and other diseases with highly heterogeneous presentation should be assessed on individual basis, although their scores may still be calculated and used in justification of the recommendation (34).

In some cases, indirect evidence obtained from coworkers, employers, and cohabitants may contribute to the establishment of general recommendations in regard to driving and machinery operating ability (Table 17.3).

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